The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Monitoring of flue gas parameters, such as carbon monoxide (“CO”), Nitrogen Oxides (“NOx”), and Oxygen (“O2”) in a fuel fired appliance, such as a gas fired water heater, is desirable to alert surrounding inhabitants of specific levels of such exhaust gas parameters. Traditionally, such gas parameter monitoring was accomplished with a device located some distance away from the actual flow of hot, combusted flue gases. Such known devices, however, may not satisfactorily measure such gas parameters because they must be located away from the actual flow of the hot, post-combustion flue gases. This is because locating such a detection device in the actual flow of the combustion gases may subject the device to temperatures above 200 degrees Celsius, which may potentially damage the sensing instrument or its exterior casing. Locating a sensor away from the actual flow of combusted gases may delay detection, and locating a device in such a flow within a flue, may cause a sensor to become damaged and inoperable.
Additionally, when an exhaust gas parameter measuring device, such as a CO sensor, is located outside of the exhaust flow, in a reduced temperature zone, the device may only detect emission parameters when the combustion exhaust is blocked downstream of the detecting device, that is, blocked above the detecting device in a chimney. In such an instance, the exhaust flue gases are normally caused to “back up” and overflow outside of a draft hood until the combustion gases reach the detecting device located outside of the proximity of the exhaust flow. This may delay detection.
In the alternative, if the air intake, that is, the air upstream of a CO detecting device is restricted or blocked, but the exhaust flue downstream of a CO detecting device is not blocked, a CO gas detecting device located outside of the combustion exhaust flow is not capable of detecting exhaust gas CO levels that may result from improper combustion. This is because the exhaust flue is free from blockage and the flue gas parameter detecting device is located outside of the exhaust flow. The exhaust gas will not “back up” and alternatively flow toward such a device when only the airflow upstream of the sensor is compromised.
What is needed then is a device that does not suffer from the above limitations. This will result in an exhaust gas parameter detection device that detects gas parameters under all operating conditions, even when an exhaust flue is restricted downstream or upstream of the device.